Characterization and probiotic properties of Bacillus strains isolated from broiler

Abstract

In order to isolate local strain of spore-forming bacteria having probiotic properties, 164 isolates of the spore-forming bacteria were isolated from 152 samples including duodenum, jejunum, ileum and cecum collected from 38 local backyard chickens raised in the northern part of Thailand. These isolates were preliminarily screened for antibiotic susceptibility and antimicrobial acitivity. Only antibiotic-susceptible isolates with antimicrobial activity were further characterized for the ability to resist certain harsh environments. Identification of the potential isolates was carried out by morphological and biochemical studies, followed by analysis of 16S rDNA sequence. Of these isolates, only one strain designated T3-1 showed antimicrobial activity against Clostridium perfringens ATCC 15191 and was susceptible to antibiotics widely used in medical treatment. Based on its morphology, biochemical property and 16S rDNA sequence, T3-1 was identified as Bacillus sp. Spore of this strain was resistant to simulated gastric and small intestinal juices, high temperature up to 100°C and could survive in water containing 5 ppm chlorine residues for 120 min. In addition, Bacillus sp. T3-1 was demonstrated to have the ability to colonize Caco2 cells as well as to produce cellulase. These findings demonstrated that Bacillus sp. T3-1, a local spore forming isolate, has probiotic properties which can be further developed as poultry feed additive.